1. Field of the Invention
This invention concerns an imaging apparatus for observing the surface of an object to be observed, which is particularly suitable to a magnifying imaging apparatus for observing skins or scalps of users under magnification in a case where cosmetic salesstuffs decide cosmetics or shampoos or rinses optimal to the users in accordance with conditions of users skins or scalps.
2. Related Art Statement
Recently, various measuring instruments and diagnostic instruments have been introduced not only in cosmetic counters of department stores but also in cosmetic stores in shopping streets.
Among all, magnifying observation apparatus such as CCD microscopes have become important as sales promotion aids since they can display skins to such a high magnification ratio as can not be seen usually, and salesstuffs can explain users while displaying, on a monitor, images of fine textures of skins formed by fine lines running in various directions, stains and freckles and roughened state of skins.
By the way, when skins are observed, the magnification ratio has to be changed depending on an object to be observed. For example, in a case of observing fine skin textures formed by fine lines running in various directions, it is preferred to pick-up images for a range of 1 to 2 cm diameter at a relatively low magnification ratio. On the other hand, in a case of closely observing individual textures, it is preferred to pick-up images for an extremely defined area of 1 to 2 mm diameter at a high magnification ratio.
Then, images in a range for 1 to 2 cm diameter can be picked-up by using a lens at a magnification ratio of about 20 and those in a range for 1 to 2 mm diameter can be picked-up by using a lens at a magnification ratio of about 200. The amount of light per unit area required for picking-up images is different between the magnification ratios 20 and 200.
Accordingly, as shown in FIG. 3, in an existent imaging apparatus 41, a main body 43 having an imaging device 42 for picking-up images of an object is mounted with an exchangeable lens unit 45 having a magnifying lens 44 at an optional magnification ratio, main body 43 is formed with a power supply contact 46, and white LEDs 47, 47, - - - that emit light upon receiving electric power from the contacts 46 are arranged circularly to each lens unit 45.
With the constitution described above, since the number, the kind and the attaching position of the light emitting device 47 can be designed optionally in accordance with the magnification ratio of the lens 44, an appropriate illumination light can be applied to the object in accordance with the magnification ratio.
However, when a plurality of white LEDs 47, - - - are arranged circularly on every exchangeable lens unit 45, it results in a problem of increasing the cost for manufacturing the exchangeable lens unit 45.
Further, in LEDs 47, - - - in the light emitting region of 1 to 2 mm diameter, the outer diameter of the casing thereof is about 3 to 4 mm. Then, even when they are arranged circularly in close contact to the each other with no gaps, a gap is inevitably formed between each of the adjacent light emitting regions.
Assuming a case where LEDs 47, - - - are circularly arranged in a narrow exchangeable lens unit 45, since the number of LEDs 47 is utmost 9 to 12, the angle of center thereof is 30 to 40° and each of the LEDs 47, - - - is imaged as a bright spot to the object when the magnification ratio is high.
For example, in a case of observing individual textures of skins at a high magnification ratio, since light of the LEDs 47, - - - is reflected as the bright spot at the edges as the boundaries between cutaneous trenches and protrusions, the edges can not be imaged clearly.
Further, lights of three primary colors are illuminated substantially uniformly from the white LED 47 but, since lights for respective colors are not completely overlapped with each other, when the lights from the LEDs 47, 47, - - - are illuminated directly to an object, the illumination light is spectralized into three colors at the peripheral edge of the illumination spot to result in a problem that images are difficult to be seen.
In view of the above, this invention intends to illuminate an appropriate illumination light in accordance with a magnification ratio to an object to be observed without providing an illumination light source such as LEDs to an imaging head such as an exchangeable lens unit, and with no polarization and with no reflection of bright spots.